1. Field of the Invention
This invention relates in general to grommets and more particularly to a two-piece grommet that wraps around the edge of a vehicle door in a pre-formed depression to route the harness from a wet side to a dry side of the door.
2. Discussion of Related Art
The process of automobile assembly is evolving to increasingly include pre-assembled modules provided to the final assembly plants of the vehicle manufacturers. An example of this is a door cassette module, comprising pre-assembled door components and wiring. Previous grommets were fit into an aperture in a hinge face of the door to route a wire harness from the vehicle electrical system into the interior of the door. However, this is cumbersome to assemble when the internal wiring of the door is required to be pre-routed on the door cassette module. In addition, the door cassette module requires a grommet that wraps around a hinge face of the door.
Current designs for these grommets are generally complex, require tolerances that are difficult to hold, need expensive molding and assembly processes, and require covers to protect long, delicate sealing edges during shipping of the module. Typically, a plastic retainer for receiving the wire harness is fit into a recess in the hinge face of the door. In one case, a steel plate over-molded with a rubber grommet is bolted to the door over the retainer. Additional components, such as the bolts, are relatively expensive. In another case, the retainer is secured in the depression by a plastic fastener and a rubber grommet is stretched over a lid for the retainer. This is a fragile design, and stretching the grommet over the lid is a difficult and critical assembly step. Both designs, the over-molded steel plate and the grommet stretched over the lid, need to be rigid to provide a force against an extended sealing surface. Feeding circuits through a hole in a steel plate or through a fragile grommet must be done carefully and is therefore time-consuming. In either case, if the tolerance or assembly prerequisites are not consistently met, the grommets do not waterproof the door wiring.
The grommet disclosed in U.S. Pat. No. 6,479,748 is an example of a prior art device for routing a wire harness from one side of a door to another. A unitary grommet is designed for use on a door body having an L-shaped opening into an interior of the door. The L-shaped opening is continuous around an edge of the door from a front surface to a side surface facing the passenger compartment. The front surface of the door includes attachment provisions for a weather strip. The grommet has front and side portions formed together at a right angle. The front portion has a recess for receiving part of the weather strip as it extends over the grommet. A wire harness protecting portion extends diagonally from the front portion to the side portion. A bellows portion stretches from the front portion to the vehicle. The wire harness is passed through the bellows portion and the front portion into the diagonal wire harness protecting portion and then out through a hole in the side portion. A groove with an adjacent outer sealing lip extends around the entire periphery of the grommet. The diagonal wire harness protecting portion is temporarily deformed during assembly to fit the edge of the L-shaped opening into the grommet groove to secure the grommet in place on both surfaces of the door. An interior trim piece is placed over the passenger side of the door to cover the harness where it is routed to the door components such as lock and window controls. The lip has to tightly seal around the entire L-shaped opening and has to secure the grommet in the opening. This means that tolerances must be carefully met. Also, it must be made difficult to deform the grommet during assemble in order to create a tight fit.
Multi-part grommets are known in the art, for example as shown in U.S. Pat. No. 6,901,627. This grommet has a flexible body for receiving and routing the harness, and a rigid inner member. The inner member extends through an opening in a vehicle panel and attaches the flexible body to the panel. This type of grommet is generally used to pass a harness directly through a vehicle panel and would be difficult to adapt to perform turning and sealing functions around the edge of a door.